1. Field of the Invention
This invention relates to an apparatus for successively forming slide fastener coupling elements by transversely cutting a blank wire of a generally Y-shape cross section, and more particularly to a slide fastener coupling element forming apparatus equipped with a coupling element discharging unit for discharging a coupling element, which has been formed and is left stuck on a bulge forming die, from the bulge forming die reliably.
2. Description of the Related Art
Conventional slide fastener coupling element forming methods of the described type are chiefly divided into two groups: one in which generally Y-shape coupling elements are formed by successively punching a continuous length of flat belt-shape metal-plate and, at the same time, bulges for successive coupling heads are formed one at a time (the resulting coupling elements will be hereinafter called "metal-plate coupling elements"); and the other in which individual coupling element blanks are obtained by threading a continuous length of blank wire through a plurality of forging rollers to shape it into a generally Y shape in cross section and then by successively cutting it into slices of a predetermined thickness using a coacting cutting punch and die, whereupon a bulge is formed at the individual coupling head of the coupling element using by a coacting bulge forming punch and die (the resulting coupling elements will be hereinafter called "wire coupling elements"). The former conventional method is exemplified by Japanese Utility Model Publication No. Sho 62-16886, and the latter conventional method is exemplified by Japanese Patent Publication No. Sho 59-27667. Subsequently, the coupling elements obtained by either conventional method are individually collected loose, or are successively attached to a fastener tape on the same apparatus.
However, since they are punched by a press or cut, either the metal-plate coupling elements plate or the wire coupling elements would be not smooth at cut surfaces and hence have to be ground. Preferably the resulting coupling elements are provided with surface treatment, such as plating, in an effort to give a high-quality look.
In the method in which the freshly formed coupling elements are attached directly to a fastener tape, plating takes place after they have been attached. This plating over the coupling elements on the insulating fastener tape could be possible by giving improvement but would be very difficult to realize in view of the high cost of production and for the complicated apparatus structure. It is also difficult to polish the leg portions of the coupling elements.
In an effort to obtain a quality product, it has been a common practice to collect the formed coupling elements in loose and then to provide over the coupling elements with a surface treatment such as polishing or plating, instead of attaching the coupling elements to the fastener tape immediately after having been formed. After the surface treatment, the coupling elements are conveyed to a slide faster manufacturing apparatus where the coupling elements are successively mounted on and along one longitudinal edge of the fastener tape at a predetermined pitch as the V-shape leg portions of the individual coupling elements are clenched.
In forming the coupling elements from a metal plate, though it is possible to freely design the coupling elements in a best shape required to be clenched on the fastener tape and in such a shape as not to obstruct the movement of a slider of the slide fastener, the rate of the non-punched-out section to punched-out section would be fairly large for a desired shape, causing a large amount of loss of material more than the amount of products. Yet if this loss could be reduced to a minimum, it would be difficult to realize the best shape.
Further, since their cut surfaces appear on the surface of the products, the metal-plate coupling elements would make a poor show, depending on the sharpness of the press. Therefore, to obtain a quality product, the metal-plate coupling elements thus obtained are polished and then plated. Besides, since a bulge for the head portion of the coupling element is formed by the press simultaneously with cutting by the press, the bulge is apt to be misshaped to give a great influence on the sliding resistance of a slider.
In forming the coupling elements from a blank wire, since the wire coupling elements formed in a generally Y-shape cross section is successively cut into slices of a predetermined thickness perpendicularly to the blank wire, it is possible to achieve a very high rate of production with no loss of material. This method is therefore most suitable for forming coupling elements.
However, in collecting the wire coupling elements from the forming die after they have been obtained by cutting the wire of a generally Y-shape cross section into slices at a predetermined pitch and forming a bulge for a coupling head portion of the coupling element, the individual coupling element will often stay on the forming die as it is left stuck thereon so that the coupling elements cannot be reliably collected up, thus making it impossible to perform the next forming, or giving damage to peripheral equipments, which therefore have to stop their operation.